Active gate control (AGC) which actively controls a gate voltage or a gate current is used as a technique for improving a trade-off between a surge voltage and a switching loss during a switching operation in a power switching element that constitutes a semiconductor power conversion device such as an inverter or a converter.
For example, Patent Literature 1 proposes a drive circuit that reduces a gate voltage to reduce a collector current when an excessive current flows through a power switching element to protect the power switching element so as not to be destroyed.
However, in Patent Literature 1, a large number of MOSFETs and resistors are required for controlling the gate current of the power switching element. Thus, a circuit scale, that is, the layout area becomes large.
Further, the technique of Patent Literature 1 controls the gate current on the basis of a resistance value of the resistor connected to the gate of the power switching element. Thus, variations in the threshold voltage caused by manufacture variations produce variations in the switching speed and variations in the switching loss. That is, the switching loss falls out of the standard defined in specifications, and yields are disadvantageously reduced.